Abstract: In each of the three largest economies with dispersed ownership of public companies—the United States, the United Kingdom, and Japan—hostile takeovers emerged under a common set of circumstances. Yet the national regulatory responses to these new market developments diverged substantially. In the United States, the Delaware judiciary became the principal source and enforcer of rules on hostile takeovers. These rules give substantial discretion to target company boards in responding to unsolicited bids. In the United Kingdom, by contrast, a private body consisting of market professionals was formed to adopt and enforce the rules on hostile bids and defenses. In contrast to those of the United States, the U.K. rules give the shareholders primary decisionmaking authority in responding to hostile takeover attempts. The hostile takeover regime in Japan, which developed recently and is still evolving, combines substantive rules with elements drawn from both the United States (Delaware) and the United Kingdom, while adding distinctive elements, including an independent enforcement role for Japan’s stock exchange.

This Article provides an analytical framework for business law development to explain the diversity in hostile takeover regimes in these three countries. The framework identifies a range of supply and demand dynamics that drives the evolution of business law in response to new market developments. It emphasizes the common role of subordinate lawmakers in filling the vacuum left by legislative inaction, and it highlights the prevalence of “preemptive lawmaking” to avoid legislation that may be contrary to the interests of important corporate governance players.

Extrapolating from the analysis of developed economies, the framework also illuminates the current stateand plausible future trajectory of hostile takeover regulation in the important emerging markets of China, India, and Brazil. A noteworthy pattern that the analysis reveals is the ostensible adoption—and adaptation—of “best practices” for hostile takeover regulation derived from Delaware and the United Kingdom in ways that protect important interests within each emerging market’s national corporate governance system.